Implantation in humans of xenogeneic tissue, i.e. tissue from a species other than human, has been carried on extensively for more than two decades. Xenogeneic implants are useful in replacing human tissues which are damaged by pathological or traumatic injury. Such implants have been used for replacing heart valves, ligaments, tendons and skin, for example. Many techniques for preparation and treatment of xenogeneic tissue have been developed for many types of prosthetic and tissue repair applications in the human body. For example, treatment of such tissue with collagen in various forms and degrees of denaturization are known (U.S. Pats. No. 3,563,228, Seiderman, 3,949,073, Daniels et al, and 4,233,360, Luck, et al.) Treatment of graft tissues with aldehydes, and glutaraldehyde in particular, is well known (see, for example, U.S. Pat. No. 3,988,872, Dardik, et al., which is but one of many disclosures of the use of glutaraldehyde in tissue treatment).
Exemplary of the state of the art are the following U.S. Patents: Angell et al, U.S. Pat. Nos. 4,035,848 and 4,247,292 and Hancock, et al, U.S. Pat. No. 4,050,893--glutaraldehyde treatment of porcine heart valves; Schechter, U.S. Pat. No. 4,120,649--glutaraldehyde treatment of pigskin, human tissue, and amniotic membranes; Holman, et al, U.S. Pat. Nos. 4,239,492 and 4,240,794--glutaraldehyde treatment of umbilical cord tissue for vascular grafts; Ketharanathan, U.S. Pat. No. 4,319,363--glutaraldehyde treatment of artificially induced tubular structure of collagenous tissue; Lentz et al, U.S. Pat. No. 4,323,358--treatment of implant tissue with glutaraldehyde and wetting agent; Wright, U.S. Pat. No. 4,350,492, and Lane, U.S. Pat. Nos. 4,372,743 and 4,443,895--heart valve prosthesis from glutaraldehyde treated porcine heart valve; Kurland, U.S. Pat. No. 4,400,833--tendons and ligaments from cows and pericardium or other porcine tissue treated with glutaraldehyde and reinforced with synthetic mesh structure mesh structure; Pollock, et al, U.S. Pat. No. 4,402,697--treatment of implant tissue with phosphate ester and glutaraldehyde; and Pollock, U.S. Pat. No. 4,405,327 treatment of implant tissue with quaternary ammonium compounds and glutaraldehyde.
The temporomandibular joint, referred to also as the TMJ, is commonly known as the lower jaw. The articulation mechanism of the temporomandibular joint comprises a glenoid cavity and an intra-articular fibrocartilage with synovial membrane above and below it, and a bony condyle. The fibrocartilage helps the condyle to glide, revolve and rotate. The fibrocartilage accepts the repetitive compressive stresses resultant from eating, speaking and mouth motions.
In the patient with degenerative bone disease, the temporomandibular joint may become dysfunctional, resulting in pain as well as loss of function, i.e. the lower jaw may simply lock in a position or have limited motion. In such patients, the fibrocartilage as well as the condylar surface have been destroyed by the degenerative processes. Currently, the primary indication for temporomandibulr joint surgery is the alleviation of pain, with little hope for recovery of full function.
There are, of course, many prosthetic and repair materials available. Synthetic materials, such as Proplast.perp. or silicone, and xenogeneic tissue or allograft tissue, such as freeze-dried dura matter (a connective tissue membrane which covers the brain), or fascia lata (a connective fibrous tissue from beneath the skin) have been tried as temporomandibular joint condylar resurfacing materials.
As more fully discussed in the copending application of the present inventor and Dr. Royce C. Lewis, Jr., entitled CROSSLINKED ANISOTROPIC XENOGENEIC DIAPHRAGM TISSUE IN FLEXOR TENDON PULLEY RECONSTRUCTION, filed on the even date herewith, the fibro-osseous sheath of the hand flexor tendon is composed of thickened areas of arced fibers (annular pulleys), alternating with crisscrossed fibers (cruciate pulleys). The function of the pulleys is to enhance flexor tendon gliding function by holding the tendons close to the phalanges to prevent them from "bowstringing" during flexion and extension.
There are also prosthetic and repair materials available for reconstruction of the flexor tendon pulley. Synthetic materials, such as Teflon.TM., dacron, Nitex.TM., and xenogeneic tissue or allograft tissue such as bovine or porcine pericardia, fascia lata, and the like have been suggested as flexor tendon pulley repair materials; however, as pointed out by Dixon and Lewis, supra, synthetics tend to be unduly bulky or thick, and can cut into the tendon, and can also result in a high inflammatory response due to particulate abrasion. Uncrosslinked or insufficiently crosslinked xenogeneic tissue and allograft tissue may lose mechanical properties as a result of rapid tissue remodeling under the stress of use, with a return of the pre-operative problems and symptoms. Available crosslinked xenogeneic tissues, such as bovine or porcine pericardial tissue, do not possess the necessary properties for the reapir of structures characterized by high pressure and relative movement and thus stretch and allow adhesion formation.
There exists a continuing and long standing need for better structural replacements for anatomical structures which are in contact with other moving anatomical structures and which are under substantial force or pressure from the moving structure. Typical of these are synovial membranes and fibrocartilage structures such as those described above.
An improved xenogeneic tissue is disclosed as the present invention which solves or greatly mitigates the problems in certain indications which are prevalent in the prior art.